The mean plasma cortisol levels for the short period from 12 to 4 PM have been found to have a very high correlation with the mean 24-hour levels of cortisol. These levels powerfully discriminate between cortisol hypersecreting depressed patients and cortisol normosecreting depressed patients or normal controls, as well as between patients with other conditions with hypersecretion (e.g., Cushing's syndrome, anorexia nervosa) and normal controls. Therefore, continuous measurement of levels of cortisol during this period has a potential for being a simplified diagnostic test for cortisol hypersecretion. The proposed project is aimed at (1) continuation of the refinement of this seemingly reliable, accurate, and convenient laboratory diagnostic test for cortisol hypersecretion in depressed patients; (2) comparison of this test to existing tests of cortisol hypersecretion, and (3) the study of the clinical and familial correlates of cortisol hypersecretion as it is measured by this test. The proposed studies are designed to establish (1) the best procedure for application of the test; (2) its reliability, and (3) its sensitivity and specificity. Simultaneously, the new test will be compared to other relevant biological tests: The mean 24-hour cortisol levels, the dexamethasone suppression test, measurements of urinary free cortisol, and 17-hydroxycorticosteroids. The correlates of the test-results will be studied in different diagnostic groups using the RDC, SADS and FH-RDC. Sleep correlates will be studied in a smaller group. Changes in clinical state will also be compared to changes in the test-results over time, using the SADS-C. The proposed project should lead to the establishment of a simple Afternoon Cortisol Test that, as part of a battery of biological tests, will contribute to better understanding and better diagnosis of conditions characterized by depressive symptoms.